Whether intracellular calcium (Ca) or voltage (V) dynamics underlies spatially discordant alternans (SDA, where neighboring regions alternate out-of-phase, separated by a nodal line) is controversial. We hypothesized that sarcoplasmic reticulum (SR) p . . .

In homogenous tissue, conduction velocity restitution (CVR) is required for the development of spatially discordant alternans (SDA) except after an ectopic beat. We hypothesized that global capture of monolayers would eliminate CV gradients and SDA wo . . .